A set of golf clubs conventionally includes a group of clubs known as woods, a group of clubs known as irons and a putter. The present invention relates particularly to the group of clubs known as woods and, more particularly, to woods of the type commonly referred to as metal woods.
A metal wood comprises a head formed of a metal material and a shaft which is secured to and which extends from the head, the head defining a receiving formation, commonly referred to as a hosel, within which an end of the shaft is secured. The shaft can be formed of any one of a range of materials and as this does not form part of the present invention, this is not described in further detail herein.
A metal wood head comprises an integrated hollow body having a front wall defining a front face of the head, known as the striking face of the head, which extends between opposite ends of the body, known as the heel and toe ends of the body, and between a base wall of the body, known as the sole of the body, and a top wall of the body. The sole and the top wall extend operatively rearwardly from the operative bottom and top edges, respectively, of the front wall and are joined to one another by a rear wall disposed at a spaced location operatively rearwardly of the striking face, thereby forming the hollow structure that optionally can be filled with a light weight foam material. A receiving formation for a golf club shaft is defined integrally as part of the body near the heel end thereof. This general construction of a metal wood head is well known and as this does not form part of the present invention, this is not described in further detail herein. Also, any reference hereinafter to a metal wood head must be interpreted as a reference to a head of the above general type.
The technology associated with the design of metal woods has continuously evolved, both in relation to the actual design of the heads and in relation to materials used. Different design parameters are associated with the use of different materials, while the level of accomplishment of a golfer intended to use a particular metal wood also must be taken into account in the design of the metal wood.
It will be understood that the main objectives of the design of a metal wood head are that it must allow a golfer to hit a golf ball the longest possible distance with the maximum possible accuracy and consistency. The distance that a golf ball is hit is largely determined by the speed at which a golfer can displace the head of his golf club during impact, with the other determining factor in distance being the flight path of the golf ball. Accuracy, which is linked to consistency, is determined by various factors which include the location on the striking face of a golf club head where a golf ball is struck. The striking face defines a "sweet spot" which is a region within which a golf ball should be struck and a current objective with golf club head design is to provide for the largest possible "sweet spot". Larger "sweet spots" are currently associated with larger golf club heads and lighter materials, titanium being a typical example of such a material which is now commonly used for forming the heads of metal woods. Any reference hereinafter to a metal wood having a head of a light metal material must accordingly be interpreted as a reference to a wood of the above type. Such a metal wood will thus include a head of a material such as titanium, or any other material or composite material which may include a metal, a synthetic plastics, or any other material, either separately or in combination, which is suitable and which may only be developed in the future. Any reference herein to a light metal material must be interpreted as such.
Because of the weight and strength and impact qualities of, for example, titanium, it has become possible to make a metal wood head larger, thereby creating a larger "sweet spot" area defined within the perimeter of the striking face of such a metal wood head, where a golf ball can be struck with relative consistency, without making the head heavier and thus slowing down the speed at which a golfer can displace the head during impact with a golf ball. Although a golfer is thus enabled to displace his golf club head at a speed normal to himself and to strike a golf ball with more consistency, known metal woods having such larger heads do not generally induce a satisfactory flight path for a golf ball and at least some of the benefits of using lighter metals as envisaged are thus forfeited. More particularly, in relation to such metal wood heads formed of light metal materials, it is required to make the sole of the head thicker than the remainder of the body of the head, thus providing for a mass concentration beneath the centre of percussion or centre of mass of the head, which will induce a golf ball to fly too high. The centre of percussion of the head of a metal wood represents the ideal position on the striking face of the head where a ball should be struck, this position coinciding with a line passing through the centre of mass of the head and extending perpendicularly to the striking face. The "sweet spot" on the striking face is an enlarged area defined by the striking face around the centre of percussion, where a ball can be struck with relative consistency.
In relation to more traditional metal woods having heads made of heavier metals, it has been attempted to provide a satisfactory flight path for a golf ball by concentrating the mass of the head in predetermined regions of the head. For example, U.S. Pat. No. 5,004,251 granted to Antonious provides for a mass concentration within a top wall region of the club head immediately above the centre of percussion of the head which, it is suggested, provides for a truer flight path if a ball is properly struck. U.S. Pat. No. 5,141,240, also granted to Antonious, in addition provides for a mass concentration within the striking face of the head in the region of the centre of percussion defined by the striking face and optionally also for mass concentrations extending rearwardly within the club head body either immediately behind the centre of percussion or on each side of the centre of percussion. Again it is suggested that such a mass arrangement will provide for a truer flight path for a ball when properly struck. In addition, it is suggested in both the above patents to define a slot in the top wall of the head above the centre of percussion, but it is stressed that this is proposed merely to enhance the aero-dynamic qualities of the club for improving club head stability while swinging the club. The mass concentrations as proposed clearly will override any effect that the formation of the said slots could have in relation to the distribution of mass within the golf club heads relative to their centre of percussion.
Insofar as the above proposals in relation to the distribution of mass within metal wood heads could enhance the flight path characteristics of a golf ball struck with such metal woods, the proposals could not be applied to the design of metal wood heads to be formed of lighter metals such as titanium, which permit the mass of heads to be maintained while the size of heads are enlarged. Particularly, the design parameters associated with the metal wood heads disclosed in the above U.S. patents cannot apply to the design of larger heads of lighter materials in order to improve the ball flight characteristics of balls struck with such larger heads.
As such, it is an object of this invention to establish design parameters for improving the ball flight characteristics associated with metal woods having heads formed of light metals, e.g. titanium, and the like.
It is a further object of this invention to provide a metal wood head formed of a light metal material which is designed to induce an improved flight path for a golf ball when properly struck, particularly when compared with the flight path of golf balls struck with known metal wood heads of the type which are formed of light metals.